Replication based security

ABSTRACT

A method, system, and computer program product for intercepting IO to a virtual machine file system by a storage based splitter, replicating, via a replication appliance, the IO to a replica of the image; the replica of the image containing a replica of the virtual machine file system, and periodically mounting the replica of the virtual machine file system to create entries for a database tracking information about the virtual machines running in the hypervisor.

A portion of the disclosure of this patent document may contain commandformats and other computer language listings, all of which are subjectto copyright protection. The copyright owner has no objection to thefacsimile reproduction by anyone of the patent document or the patentdisclosure, as it appears in the Patent and Trademark Office patent fileor records, but otherwise reserves all copyright rights whatsoever.

TECHNICAL FIELD

This invention relates to data replication.

BACKGROUND

Computer data is vital to today's organizations, and a significant partof protection against disasters is focused on data protection. Assolid-state memory has advanced to the point where cost of memory hasbecome a relatively insignificant factor, organizations can afford tooperate with systems that store and process terabytes of data.

Conventional data protection systems include tape backup drives, forstoring organizational production site data on a periodic basis. Suchsystems suffer from several drawbacks. First, they require a systemshutdown during backup, since the data being backed up cannot be usedduring the backup operation. Second, they limit the points in time towhich the production site can recover. For example, if data is backed upon a daily basis, there may be several hours of lost data in the eventof a disaster. Third, the data recovery process itself takes a longtime.

Another conventional data protection system uses data replication, bycreating a copy of the organization's production site data on asecondary backup storage system, and updating the backup with changes.The backup storage system may be situated in the same physical locationas the production storage system, or in a physically remote location.Data replication systems generally operate either at the applicationlevel, at the file system level, at the hypervisor level or at the datablock level.

Current data protection systems try to provide continuous dataprotection, which enable the organization to roll back to any specifiedpoint in time within a recent history. Continuous data protectionsystems aim to satisfy two conflicting objectives, as best as possible;namely, (i) minimize the down time, in which the organization productionsite data is unavailable, during a recovery, and (ii) enable recovery asclose as possible to any specified point in time within a recenthistory.

Continuous data protection typically uses a technology referred to as“journaling,” whereby a log is kept of changes made to the backupstorage. During a recovery, the journal entries serve as successive“undo” information, enabling rollback of the backup storage to previouspoints in time. Journaling was first implemented in database systems,and was later extended to broader data protection.

One challenge to continuous data protection is the ability of a backupsite to keep pace with the data transactions of a production site,without slowing down the production site. The overhead of journalinginherently requires several data transactions at the backup site foreach data transaction at the production site. As such, when datatransactions occur at a high rate at the production site, the backupsite may not be able to finish backing up one data transaction beforethe next production site data transaction occurs. If the production siteis not forced to slow down, then necessarily a backlog of un-logged datatransactions may build up at the backup site. Without being able tosatisfactorily adapt dynamically to changing data transaction rates, acontinuous data protection system chokes and eventually forces theproduction site to shut down.

SUMMARY

A method, system, and computer program product for intercepting IO to avirtual machine file system by a storage based splitter, replicating,via a replication appliance, the IO to a replica of the image; thereplica of the image containing a replica of the virtual machine filesystem, and periodically mounting the replica of the virtual machinefile system to create entries for a database tracking information aboutthe virtual machines running in the hypervisor.

BRIEF DESCRIPTION OF THE DRAWINGS

Objects, features, and advantages of embodiments disclosed herein may bebetter understood by referring to the following description inconjunction with the accompanying drawings. The drawings are not meantto limit the scope of the claims included herewith. For clarity, notevery element may be labeled in every Figure. The drawings are notnecessarily to scale, emphasis instead being placed upon illustratingembodiments, principles, and concepts. Thus, features and advantages ofthe present disclosure will become more apparent from the followingdetailed description of exemplary embodiments thereof taken inconjunction with the accompanying drawings in which:

FIG. 1 is a simplified illustration of a data protection system, inaccordance with an embodiment of the present disclosure;

FIG. 2 is a simplified illustration of a write transaction for ajournal, in accordance with an embodiment of the present disclosure;

FIG. 3 is a simplified illustration of a hypervisor environment, inaccordance with an embodiment of the present disclosure;

FIG. 4 is an alternative simplified illustration of a hypervisorenvironment, in accordance with an embodiment of the present disclosure;

FIG. 5 is a further simplified illustration of a hypervisor environment,in accordance with an embodiment of the present disclosure;

FIG. 6 is a simplified illustration of a hypervisor environment with ahypervisor being split at a storage layer, in accordance with anembodiment of the present disclosure;

FIG. 7a is a simplified example of a method of replicating IO at astorage level in a hypervisor environment, in accordance with anembodiment of the present disclosure;

FIG. 7b is a simplified example of a method for creating a database ofhypervisor activity using storage based replication, in accordance withan embodiment of the present disclosure;

FIG. 8 is an alternative simplified illustration of a hypervisorenvironment with a hypervisor being split at a storage layer, inaccordance with an embodiment of the present disclosure;

FIG. 9a is a simplified example of a method of replicating IO at astorage level in a hypervisor environment, in accordance with anembodiment of the present disclosure;

FIG. 9b is a simplified example of a method for updating a database ofhypervisor activity using storage based replication, in accordance withan embodiment of the present disclosure;

FIG. 10 is an further alternative simplified illustration of ahypervisor environment with a hypervisor being split at a storage layer,in accordance with an embodiment of the present disclosure;

FIG. 11 is a simplified illustration of information kept in a databasecataloging activity in hypervisor environment, in accordance with anembodiment of the present disclosure;

FIG. 12 is a simplified example of a method for analyzing a database andrestoring a virtual machine, in accordance with an embodiment of thepresent disclosure.

FIG. 13 is an example of an embodiment of an apparatus that may utilizethe techniques described herein, in accordance with an embodiment of thepresent disclosure; and

FIG. 14 is an example of an embodiment of a method embodied on acomputer readable storage medium that may utilize the techniquesdescribed herein, in accordance with an embodiment of the presentdisclosure.

DETAILED DESCRIPTION

According to a study done by Scott & Scott LLP of over 700 businesses,85% of respondents confirmed they had been the victims of a securitybreach. In many embodiments, a challenge for security with virtualmachines may be that in virtual machine environments, virtual machinesappear and disappear. In many embodiments, this may lead to dangeroussecurity issues. In some embodiments, a threat from a virtual machinemay be from an internal threat, such as an employee, or an externalthreat such as a hacker.

Typically, a hypervisor may serve as a container or virtual environmentfor one or more virtual machines. Conventionally, a virtual machine mayinteract with resources in a hypervisor and the virtual machine may beunaware that it is not a physical machine. Generally, a hypervisor mayprovide resources to a virtual machine. Usually, the hypervisortranslates physical resources, such as LUNs and processing power, intoresources able to be used by a virtual machine. Conventionally, ahypervisor stores one or more virtual machines disks together in avirtual machine file system on physical storage or on a LUN. Usually, avirtual machine file system may appear as a single file to processesoutside the hypervisor. Generally, a virtual machine may be created anddeleted in virtualized environments. Typically, some virtual machinesare long lived while others exist for short periods of time and arecreated for specific tasks. In certain embodiments herein, theapplication may refer to suspicious activity. In many embodiments,suspicious activity may indicate activity that is outside of theordinary and may indicate a hacker or other data breach.

In certain embodiments as used herein, reference may be made to astorage layer. In most embodiments, a storage layer may be outside ofand not visible to a virtual machine inside a hypervisor. In manyembodiments, a hypervisor layer may provide a layer of abstraction thatabstracts away the physical storage or logical storage that existsoutside of the hypervisor. In almost all embodiments, a virtual machinemay be ignorant of and unable to examine the storage layer outside ofthe hypervisor.

In most embodiments, if someone has access to a virtual infrastructure,then generally that person may be able to cause significant damage tothat environment. In many embodiments, if an attacker destroyed avirtual machine that the attacker was using, then there may be no recordof the content of the virtual machine. In certain embodiments, if anattacker had access to a virtual infrastructure, the attacker may beable to delete logs and mask or remove evidence of the existence of anycreated virtual machines.

In some embodiments, an indication of data associated with a destroyedvirtual machine may be auditing logs of a hypervisor which may includecreation and deletion time of the VM. Typical backup technologies maynot be good enough to trace what a destroyed virtual machine did as a VMmay be created and deleted within a backup window, leaving little to notrace of the VM when a back-up occurs. Usually, if a back-up window isevery day, then a user may only know what VMs existed at the time of daythe back-up was taken. In some embodiments, a user with access toauditing logs of a hypervisor may be able to delete the logs, or thelogs may be corrupted in a production environment. In other embodiments,if nothing more than the creation and deletion time of a VM isavailable, little analysis may be done on that VM.

In some embodiments, replication of one or more LUNs on which VM data isstored may enable access to a VM that has been deleted. In certainembodiments, replication of LUNs containing data storage of a hypervisormay be from a backend storage array using a continuous data protectiontechnology. In most embodiments, replication at a storage array may beoutside of and unreachable from within a hypervisor. In manyembodiments, a virtual machine within a hypervisor may have no way todetect replication outside of the hypervisor or on a storage array. Incertain embodiments, an attacker using a virtual machine may have noknowledge or way to detect that the actions of the virtual machine arebeing traced in a physical infrastructure.

In most embodiments, a splitter resident outside of a hypervisor maysplit IO written by the hypervisor at the storage layer to a replicationappliance. In some embodiments, a storage layer splitter may create areplica copy of a hypervisor's virtual machine file system containingvirtual machines along with a journal enabling any point in time accessto the volume containing the virtual machines. In most embodiments,split IO may enable access to any point in time within a givenprotection window. In many embodiments, split IO may track each IO thatoccurs in a virtual environment. In certain embodiments, split IO maycreate a continuous data protection copy of IO written to a productionsite for later analysis. In some embodiments, split IO may create acontinuous data protection copy of IO written to a replication site forlater analysis. In many embodiments, a system may periodically access apoint in time using split IO. In certain embodiments, an accessedpointed in time may be used to mount a VMFS to a replication appliance.In most embodiments, a mounted VMFS may be analyzed to determineinformation about a virtual environment. In some embodiments,information about a virtual environment may include how many virtualmachines are present and what files the virtual machines are accessing.

In at least some embodiments, a replication appliance may parse a VMFS.In some embodiments, a replication appliance may create a database ofcurrently available VMs at a given point in time. In certainembodiments, a replication appliance may mount a VMDK at a point in timeand add a list of file within the VMDKs to a database. In manyembodiments, a database may include auditing information such as who orwhat process created the VMs. In most embodiments, using continuous dataprotection, any point in time within a given time frame may be accessed,which may enable access to any virtual machine created or destroyedwithin that time window. In almost all embodiments, access to a virtualmachine within a protection window may enable analysis of the activitiesof that virtual machine within the protection window.

In further embodiments, if suspicious activity is discovered, a databasemay be searched and a suspicious virtual machine may be restored. Insome embodiments, an analytics engine may run on a database of virtualmachines to look for suspicious activities. In certain embodiments,creation or deletion of one or more VMs too often may denote asuspicious activity. In other embodiments, a given file name or filecontent may denote a suspicious activity.

In most embodiments, when replication is performed on a backend storagearray, a person without access to the storage array may not be able tocorrupt or hide data on that storage array, even if that person orprocess has full access to a virtualization and hypervisor layer. Inmany embodiments, processing may be performed at a replica appliance atreplica storage and the processing may not interfere with or benoticeable by virtual machines running in production environment. Inmany embodiments, continuous data protection (CDP) monitoring may enabletracking activities of a suspicious virtual machine and recover thevirtual machine to any point in time. In many embodiments, being able torecover changes in a virtual machine may lead to information about abreach.

The following may be helpful in understanding the specification andclaims:

BACKUP SITE—may be a facility where replicated production site data isstored; the backup site may be located in a remote site or at the samelocation as the production site; a backup site may be a virtual orphysical site; a backup site may be referred to alternatively as areplica site or a replication site;

CLONE—a clone may be a copy or clone of the image or images, drive ordrives of a first location at a second location;

DELTA MARKING STREAM—may mean the tracking of the delta between theproduction and replication site, which may contain the meta data ofchanged locations, the delta marking stream may be kept persistently onthe journal at the production site of the replication, based on thedelta marking data the DPA knows which locations are different betweenthe production and the replica and transfers them to the replica to makeboth sites identical.

DPA—may be Data Protection Appliance a computer or a cluster ofcomputers, or a set of processes that serve as a data protectionappliance, responsible for data protection services including inter aliadata replication of a storage system, and journaling of I/O requestsissued by a host computer to the storage system; The DPA may be aphysical device, a virtual device running, or may be a combination of avirtual and physical device.

RPA—may be replication protection appliance, is another name for DPA. AnRPA may be a virtual DPA or a physical DPA.

HOST—may be at least one computer or networks of computers that runs atleast one data processing application that issues I/O requests to one ormore storage systems; a host is an initiator with a SAN; a host may be avirtual machine

HOST DEVICE—may be an internal interface in a host, to a logical storageunit;

IMAGE—may be a copy of a logical storage unit at a specific point intime;

INITIATOR—may be a node in a SAN that issues I/O requests;

JOURNAL—may be a record of write transactions issued to a storagesystem; used to maintain a duplicate storage system, and to rollback theduplicate storage system to a previous point in time;

LOGICAL UNIT—may be a logical entity provided by a storage system foraccessing data from the storage system;

LUN—may be a logical unit number for identifying a logical unit; mayalso refer to one or more virtual disks or virtual LUNs, which maycorrespond to one or more Virtual Machines. As used herein, LUN and LUmay be used interchangeably to refer to a LU.

Management and deployment tools—may provide the means to deploy, controland manage the RP solution through the virtual environment managementtools

PHYSICAL STORAGE UNIT—may be a physical entity, such as a disk or anarray of disks, for storing data in storage locations that can beaccessed by address;

PRODUCTION SITE—may be a facility where one or more host computers rundata processing applications that write data to a storage system andread data from the storage system; may be a virtual or physical site.

SAN—may be a storage area network of nodes that send and receive I/O andother requests, each node in the network being an initiator or a target,or both an initiator and a target;

SOURCE SIDE—may be a transmitter of data within a data replicationworkflow, during normal operation a production site is the source side;and during data recovery a backup site is the source side; may be avirtual or physical site

SNAPSHOT-a Snapshot may refer to differential representations of animage, i.e. the snapshot may have pointers to the original volume, andmay point to log volumes for changed locations. Snapshots may becombined into a snapshot array, which may represent different imagesover a time period.

STORAGE SYSTEM—may be a SAN entity that provides multiple logical unitsfor access by multiple SAN initiators

TARGET—may be a node in a SAN that replies to I/O requests;

TARGET SIDE—may be a receiver of data within a data replicationworkflow; during normal operation a back site is the target side, andduring data recovery a production site is the target side; may be avirtual or physical site

WAN—may be a wide area network that connects local networks and enablesthem to communicate with one another, such as the Internet.

SPLITTER/PROTECTION AGENT: may be an agent running either on aproduction host a switch or a storage array which can intercept IO andsplit them to a DPA and to the storage array, fail IO redirect IO or doany other manipulation to the IO; the splitter or protection agent maybe used in both physical and virtual systems. The splitter may be in theIO stack of a system and may be located in the hypervisor for virtualmachines. May be referred to herein as an Open Replicator Splitter(ORS).

VIRTUAL VOLUME: may be a volume which is exposed to host by avirtualization layer, the virtual volume may be spanned across more thanone site and or volumes

VASA: may be a set of vCenter providers that allow an administrator tomanage storage

VMFS: may be a virtual machine file system, a file system provided byVMware for storing a virtual machine

VMDK: may be a virtual machine disk file containing a disk data in aVMFS. Analog to a LUN in a block storage array

Virtual RPA (vRPA)/Virtual DPA (vDPA): may be a DPA running in a VM.

VASA may be vSphere Storage application program interfaces (APIs) forStorage Awareness.

MARKING ON SPLITTER: may be a mode in a splitter where intercepted IOsare not split to an appliance and the storage, but changes (meta data)are tracked in a list and/or a bitmap and I/O is immediately sent todown the IO stack.

FAIL ALL MODE: may be a mode of a volume in the splitter where all writeand read IOs intercepted by the splitter are failed to the host, butother SCSI commands like read capacity are served.

LOGGED ACCESS: may be an access method provided by the appliance and thesplitter, in which the appliance rolls the volumes of the consistencygroup to the point in time the user requested and let the host accessthe volumes in a copy on first write base.

VIRTUAL ACCESS: may be an access method provided by the appliance andthe splitter, in which the appliance exposes a virtual volume from aspecific point in time to the host, the data for the virtual volume ispartially stored on the remote copy and partially stored on the journal.

CDP: Continuous Data Protection, may refer to a full replica of a volumeor a set of volumes along with a journal which allows any point in timeaccess, the CDP copy is at the same site, and maybe the same storagearray of the production site CRR: Continuous Remote Replica may refer toa full replica of a volume or a set of volumes along with a journalwhich allows any point in time access at a site remote to the productionvolume and on a separate storage array.

A description of journaling and some techniques associated withjournaling may be described in the patent titled METHODS AND APPARATUSFOR OPTIMAL JOURNALING FOR CONTINUOUS DATA REPLICATION and with U.S.Pat. No. 7,516,287, and METHODS AND APPARATUS FOR OPTIMAL JOURNALING FORCONTINUOUS DATA REPLICATION and with U.S. Pat. No. 8,332,687, which arehereby incorporated by reference. A description of synchronous andasynchronous replication may be described in the patent titledDYNAMICALLY SWITCHING BETWEEN SYNCHRONOUS AND ASYNCHRONOUS REPLICATIONand with U.S. Pat. No. 8,341,115, which is hereby incorporated byreference.

A discussion of image access may be found in U.S. patent applicationSer. No. 12/969,903 entitled “DYNAMIC LUN RESIZING IN A REPLICATIONENVIRONMENT” filed on Dec. 16, 2010 assigned to EMC Corp., which ishereby incorporated by reference.

Description of Embodiments Using of a Five State Journaling Process

Reference is now made to FIG. 1, which is a simplified illustration of adata protection system 100, in accordance with an embodiment of thepresent invention. Shown in FIG. 1 are two sites; Site I, which is aproduction site, on the right, and Site II, which is a backup site, onthe left. Under normal operation the production site is the source sideof system 100, and the backup site is the target side of the system. Thebackup site is responsible for replicating production site data.Additionally, the backup site enables rollback of Site I data to anearlier pointing time, which may be used in the event of data corruptionof a disaster, or alternatively in order to view or to access data froman earlier point in time.

During normal operations, the direction of replicate data flow goes fromsource side to target side. It is possible, however, for a user toreverse the direction of replicate data flow, in which case Site Istarts to behave as a target backup site, and Site II starts to behaveas a source production site. Such change of replication direction isreferred to as a “failover”. A failover may be performed in the event ofa disaster at the production site, or for other reasons. In some dataarchitectures, Site I or Site II behaves as a production site for aportion of stored data, and behaves simultaneously as a backup site foranother portion of stored data. In some data architectures, a portion ofstored data is replicated to a backup site, and another portion is not.

The production site and the backup site may be remote from one another,or they may both be situated at a common site, local to one another.Local data protection has the advantage of minimizing data lag betweentarget and source, and remote data protection has the advantage is beingrobust in the event that a disaster occurs at the source side.

The source and target sides communicate via a wide area network (WAN)128, although other types of networks are also adaptable for use withthe present invention.

In accordance with an embodiment of the present invention, each side ofsystem 100 includes three major components coupled via a storage areanetwork (SAN); namely, (i) a storage system, (ii) a host computer, and(iii) a data protection appliance (DPA). Specifically with reference toFIG. 1, the source side SAN includes a source host computer 104, asource storage system 108, and a source DPA 112. Similarly, the targetside SAN includes a target host computer 116, a target storage system120, and a target DPA 124.

Generally, a SAN includes one or more devices, referred to as “nodes”. Anode in a SAN may be an “initiator” or a “target”, or both. An initiatornode is a device that is able to initiate requests to one or more otherdevices; and a target node is a device that is able to reply torequests, such as SCSI commands, sent by an initiator node. A SAN mayalso include network switches, such as fiber channel switches. Thecommunication links between each host computer and its correspondingstorage system may be any appropriate medium suitable for data transfer,such as fiber communication channel links.

In an embodiment of the present invention, the host communicates withits corresponding storage system using small computer system interface(SCSI) commands.

System 100 includes source storage system 108 and target storage system120. Each storage system includes physical storage units for storingdata, such as disks or arrays of disks. Typically, storage systems 108and 120 are target nodes. In order to enable initiators to send requeststo storage system 108, storage system 108 exposes one or more logicalunits (LU) to which commands are issued. Thus, storage systems 108 and120 are SAN entities that provide multiple logical units for access bymultiple SAN initiators.

Logical units are a logical entity provided by a storage system, foraccessing data stored in the storage system. A logical unit isidentified by a unique logical unit number (LUN). In an embodiment ofthe present invention, storage system 108 exposes a logical unit 136,designated as LU A, and storage system 120 exposes a logical unit 156,designated as LU B.

In an embodiment of the present invention, LU B is used for replicatingLU A. As such, LU B is generated as a copy of LU A. In one embodiment,LU B is configured so that its size is identical to the size of LU A.Thus for LU A, storage system 120 serves as a backup for source sidestorage system 108. Alternatively, as mentioned hereinabove, somelogical units of storage system 120 may be used to back up logical unitsof storage system 108, and other logical units of storage system 120 maybe used for other purposes. Moreover, in certain embodiments of thepresent invention, there is symmetric replication whereby some logicalunits of storage system 108 are used for replicating logical units ofstorage system 120, and other logical units of storage system 120 areused for replicating other logical units of storage system 108.

System 100 includes a source side host computer 104 and a target sidehost computer 116. A host computer may be one computer, or a pluralityof computers, or a network of distributed computers, each computer mayinclude inter alia a conventional CPU, volatile and non-volatile memory,a data bus, an I/O interface, a display interface and a networkinterface. Generally a host computer runs at least one data processingapplication, such as a database application and an e-mail server.

Generally, an operating system of a host computer creates a host devicefor each logical unit exposed by a storage system in the host computerSAN. A host device is a logical entity in a host computer, through whicha host computer may access a logical unit. In an embodiment of thepresent invention, host device 104 identifies LU A and generates acorresponding host device 140, designated as Device A, through which itcan access LU A. Similarly, host computer 116 identifies LU B andgenerates a corresponding device 160, designated as Device B.

In an embodiment of the present invention, in the course of continuousoperation, host computer 104 is a SAN initiator that issues I/O requests(write/read operations) through host device 140 to LU A using, forexample, SCSI commands. Such requests are generally transmitted to LU Awith an address that includes a specific device identifier, an offsetwithin the device, and a data size. Offsets are generally aligned to 512byte blocks. The average size of a write operation issued by hostcomputer 104 may be, for example, 10 kilobytes (KB); i.e., 20 blocks.For an I/O rate of 50 megabytes (MB) per second, this corresponds toapproximately 5,000 write transactions per second.

System 100 includes two data protection appliances, a source side DPA112 and a target side DPA 124. A DPA performs various data protectionservices, such as data replication of a storage system, and journalingof I/O requests issued by a host computer to source side storage systemdata. As explained in detail hereinbelow, when acting as a target sideDPA, a DPA may also enable rollback of data to an earlier point in time,and processing of rolled back data at the target site. Each DPA 112 and124 is a computer that includes inter alia one or more conventional CPUsand internal memory.

For additional safety precaution, each DPA is a cluster of suchcomputers. Use of a cluster ensures that if a DPA computer is down, thenthe DPA functionality switches over to another computer. The DPAcomputers within a DPA cluster communicate with one another using atleast one communication link suitable for data transfer via fiberchannel or IP based protocols, or such other transfer protocol. Onecomputer from the DPA cluster serves as the DPA leader. The DPA clusterleader coordinates between the computers in the cluster, and may alsoperform other tasks that require coordination between the computers,such as load balancing.

In the architecture illustrated in FIG. 1, DPA 112 and DPA 124 arestandalone devices integrated within a SAN. Alternatively, each of DPA112 and DPA 124 may be integrated into storage system 108 and storagesystem 120, respectively, or integrated into host computer 104 and hostcomputer 116, respectively. Both DPAs communicate with their respectivehost computers through communication lines such as fiber channels using,for example, SCSI commands.

In accordance with an embodiment of the present invention, DPAs 112 and124 are configured to act as initiators in the SAN; i.e., they can issueI/O requests using, for example, SCSI commands, to access logical unitson their respective storage systems. DPA 112 and DPA 124 are alsoconfigured with the necessary functionality to act as targets; i.e., toreply to I/O requests, such as SCSI commands, issued by other initiatorsin the SAN, including inter alia their respective host computers 104 and116. Being target nodes, DPA 112 and DPA 124 may dynamically expose orremove one or more logical units.

As described hereinabove, Site I and Site II may each behavesimultaneously as a production site and a backup site for differentlogical units. As such, DPA 112 and DPA 124 may each behave as a sourceDPA for some logical units and as a target DPA for other logical units,at the same time.

In accordance with an embodiment of the present invention, host computer104 and host computer 116 include protection agents 144 and 164,respectively. Protection agents 144 and 164 intercept SCSI commandsissued by their respective host computers, via host devices to logicalunits that are accessible to the host computers. In accordance with anembodiment of the present invention, a data protection agent may act onan intercepted SCSI commands issued to a logical unit, in one of thefollowing ways:

Send the SCSI commands to its intended logical unit.

Redirect the SCSI command to another logical unit.

Split the SCSI command by sending it first to the respective DPA. Afterthe DPA returns an acknowledgement, send the SCSI command to itsintended logical unit.

Fail a SCSI command by returning an error return code.

Delay a SCSI command by not returning an acknowledgement to therespective host computer.

A protection agent may handle different SCSI commands, differently,according to the type of the command. For example, a SCSI commandinquiring about the size of a certain logical unit may be sent directlyto that logical unit, while a SCSI write command may be split and sentfirst to a DPA associated with the agent. A protection agent may alsochange its behavior for handling SCSI commands, for example as a resultof an instruction received from the DPA.

Specifically, the behavior of a protection agent for a certain hostdevice generally corresponds to the behavior of its associated DPA withrespect to the logical unit of the host device. When a DPA behaves as asource site DPA for a certain logical unit, then during normal course ofoperation, the associated protection agent splits I/O requests issued bya host computer to the host device corresponding to that logical unit.Similarly, when a DPA behaves as a target device for a certain logicalunit, then during normal course of operation, the associated protectionagent fails I/O requests issued by host computer to the host devicecorresponding to that logical unit.

Communication between protection agents and their respective DPAs mayuse any protocol suitable for data transfer within a SAN, such as fiberchannel, or SCSI over fiber channel. The communication may be direct, orvia a logical unit exposed by the DPA. In an embodiment of the presentinvention, protection agents communicate with their respective DPAs bysending SCSI commands over fiber channel.

In an embodiment of the present invention, protection agents 144 and 164are drivers located in their respective host computers 104 and 116.Alternatively, a protection agent may also be located in a fiber channelswitch, or in any other device situated in a data path between a hostcomputer and a storage system.

What follows is a detailed description of system behavior under normalproduction mode, and under recovery mode.

In accordance with an embodiment of the present invention, in productionmode DPA 112 acts as a source site DPA for LU A. Thus, protection agent144 is configured to act as a source side protection agent; i.e., as asplitter for host device A. Specifically, protection agent 144replicates SCSI I/O requests. A replicated SCSI I/O request is sent toDPA 112. After receiving an acknowledgement from DPA 124, protectionagent 144 then sends the SCSI I/O request to LU A. Only after receivinga second acknowledgement from storage system 108 may host computer 104initiate another I/O request.

When DPA 112 receives a replicated SCSI write request from dataprotection agent 144, DPA 112 transmits certain I/O informationcharacterizing the write request, packaged as a “write transaction”,over WAN 128 to DPA 124 on the target side, for journaling and forincorporation within target storage system 120.

DPA 112 may send its write transactions to DPA 124 using a variety ofmodes of transmission, including inter alia (i) a synchronous mode, (ii)an asynchronous mode, and (iii) a snapshot mode. In synchronous mode,DPA 112 sends each write transaction to DPA 124, receives back anacknowledgement from DPA 124, and in turns sends an acknowledgement backto protection agent 144. Protection agent 144 waits until receipt ofsuch acknowledgement before sending the SCSI write request to LU A.

In asynchronous mode, DPA 112 sends an acknowledgement to protectionagent 144 upon receipt of each I/O request, before receiving anacknowledgement back from DPA 124.

In snapshot mode, DPA 112 receives several I/O requests and combinesthem into an aggregate “snapshot” of all write activity performed in themultiple I/O requests, and sends the snapshot to DPA 124, for journalingand for incorporation in target storage system 120. In snapshot mode DPA112 also sends an acknowledgement to protection agent 144 upon receiptof each I/O request, before receiving an acknowledgement back from DPA124.

For the sake of clarity, the ensuing discussion assumes that informationis transmitted at write-by-write granularity.

While in production mode, DPA 124 receives replicated data of LU A fromDPA 112, and performs journaling and writing to storage system 120. Whenapplying write operations to storage system 120, DPA 124 acts as aninitiator, and sends SCSI commands to LU B.

During a recovery mode, DPA 124 undoes the write transactions in thejournal, so as to restore storage system 120 to the state it was at, atan earlier time.

As described hereinabove, in accordance with an embodiment of thepresent invention, LU B is used as a backup of LU A. As such, duringnormal production mode, while data written to LU A by host computer 104is replicated from LU A to LU B, host computer 116 should not be sendingI/O requests to LU B. To prevent such I/O requests from being sent,protection agent 164 acts as a target site protection agent for hostDevice B and fails I/O requests sent from host computer 116 to LU Bthrough host Device B.

In accordance with an embodiment of the present invention, targetstorage system 120 exposes a logical unit 176, referred to as a “journalLU”, for maintaining a history of write transactions made to LU B,referred to as a “journal”. Alternatively, journal LU 176 may be stripedover several logical units, or may reside within all of or a portion ofanother logical unit. DPA 124 includes a journal processor 180 formanaging the journal.

Journal processor 180 functions generally to manage the journal entriesof LU B. Specifically, journal processor 180 (i) enters writetransactions received by DPA 124 from DPA 112 into the journal, bywriting them into the journal LU, (ii) applies the journal transactionsto LU B, and (iii) updates the journal entries in the journal LU withundo information and removes already-applied transactions from thejournal. As described below, with reference to FIGS. 2 and 3A-3D,journal entries include four streams, two of which are written whenwrite transaction are entered into the journal, and two of which arewritten when write transaction are applied and removed from the journal.

Reference is now made to FIG. 2, which is a simplified illustration of awrite transaction 200 for a journal, in accordance with an embodiment ofthe present invention. The journal may be used to provide an adaptor foraccess to storage 120 at the state it was in at any specified point intime. Since the journal contains the “undo” information necessary torollback storage system 120, data that was stored in specific memorylocations at the specified point in time may be obtained by undoingwrite transactions that occurred subsequent to such point in time.

Write transaction 200 generally includes the following fields:

one or more identifiers;

a time stamp, which is the date & time at which the transaction wasreceived by source side DPA 112;

a write size, which is the size of the data block;

a location in journal LU 176 where the data is entered;

a location in LU B where the data is to be written; and

the data itself.

Write transaction 200 is transmitted from source side DPA 112 to targetside DPA 124. As shown in FIG. 2, DPA 124 records the write transaction200 in four streams. A first stream, referred to as a DO stream,includes new data for writing in LU B. A second stream, referred to asan DO METADATA stream, includes metadata for the write transaction, suchas an identifier, a date & time, a write size, a beginning address in LUB for writing the new data in, and a pointer to the offset in the dostream where the corresponding data is located. Similarly, a thirdstream, referred to as an UNDO stream, includes old data that wasoverwritten in LU B; and a fourth stream, referred to as an UNDOMETADATA, include an identifier, a date & time, a write size, abeginning address in LU B where data was to be overwritten, and apointer to the offset in the undo stream where the corresponding olddata is located.

In practice each of the four streams holds a plurality of writetransaction data. As write transactions are received dynamically bytarget DPA 124, they are recorded at the end of the DO stream and theend of the DO METADATA stream, prior to committing the transaction.During transaction application, when the various write transactions areapplied to LU B, prior to writing the new DO data into addresses withinthe storage system, the older data currently located in such addressesis recorded into the UNDO stream.

By recording old data, a journal entry can be used to “undo” a writetransaction. To undo a transaction, old data is read from the UNDOstream in a reverse order, from the most recent data to the oldest data,for writing into addresses within LU B. Prior to writing the UNDO datainto these addresses, the newer data residing in such addresses isrecorded in the DO stream.

The journal LU is partitioned into segments with a pre-defined size,such as 1 MB segments, with each segment identified by a counter. Thecollection of such segments forms a segment pool for the four journalingstreams described hereinabove. Each such stream is structured as anordered list of segments, into which the stream data is written, andincludes two pointers—a beginning pointer that points to the firstsegment in the list and an end pointer that points to the last segmentin the list.

According to a write direction for each stream, write transaction datais appended to the stream either at the end, for a forward direction, orat the beginning, for a backward direction. As each write transaction isreceived by DPA 124, its size is checked to determine if it can fitwithin available segments. If not, then one or more segments are chosenfrom the segment pool and appended to the stream's ordered list ofsegments.

Thereafter the DO data is written into the DO stream, and the pointer tothe appropriate first or last segment is updated. Freeing of segments inthe ordered list is performed by simply changing the beginning or theend pointer. Freed segments are returned to the segment pool for re-use.

A journal may be made of any number of streams including less than ormore than 5 streams. Often, based on the speed of the journaling andwhether the back-up is synchronous or a synchronous a fewer or greaternumber of streams may be used.

Virtual Machines

Refer now to the example embodiment of FIG. 3, which illustrates asample hypervisor writing to storage at a first point in time. In FIG.3, production site 300 has hypervisor 310. Hypervisor 310 has VM 330 andVM 331. VM 330 sends IO 305 to VMDK 370, which is in VMFS 365, stored onvolume 360 on storage array 350. VM 331 sends IO 306 to VMDK 371, whichis in VMFS 365, stored on volume 360 on storage array 350. Hypervisor310 abstracts storage 350 and volume 360 from VMs 330 and 331 bypresenting each VM with an associated virtual machine disk. VMS 330 and331 have no knowledge of storage 350 or volume 360, rather are aware oftheir respective VMDKs.

Refer now to the example embodiment of FIG. 4, which illustrates asample hypervisor writing to storage at a second period of time. In FIG.4, production site 400 has hypervisor 410. Hypervisor 410 has VM 431, VM432, and VM 433. VM 431 sends IO 405 to VMDK 471, which is in VMFS 465,stored on volume 460 on storage array 450. VM 432 sends IO 406 to VMDK472, which is in VMFS 465, stored on volume 460 on storage array 450. VM433 sends IO 408 to VMDK 473, which is in VMFS 465, stored on volume 460on storage array 450. Hypervisor 410 abstracts storage 450 and volume460 from VMs 431, 432 and 433 by presenting each VM with an associatedvirtual machine disk. VMS 431, 432, and 433 have no knowledge of storage450 or volume 460, rather are aware of their respective VMDKs. Note, inthis embodiment, there is an additional virtual machine, VM 433 whichhas been created.

Refer now to the example embodiment of FIG. 5, which illustrates asample hypervisor writing to storage at a third period of time. In FIG.5, production site 500 has hypervisor 510. Hypervisor 510 has VM 531 andVM 532. VM 531 sends IO 505 to VMDK 571, which is in VMFS 565, stored onvolume 360 on storage array 550. VM 532 sends IO 506 to VMDK 572, whichis in VMFS 565, stored on volume 560 on storage array 550. Hypervisor510 abstracts storage 550 and volume 560 from VMs 531, and 532 bypresenting each VM with an associated virtual machine disk. VMS 531 and532 have no knowledge of storage 550 or volume 560, rather are aware oftheir respective VMDKs. Note, in this embodiment, there is are only twovirtual machines and the virtual machine 433 from time T2 in FIG. 4 hasdisappeared.

In many embodiments, such as those of FIGS. 3-5, if there was not aback-up of the hypervisor at each increment of time T, the existence ofa virtual machine, such as VM 433 in FIG. 4 may not have been noticedand the data of the VM may not be recoverable. In certain embodiments, aback-up window is set to a time large enough that a virtual machine maybe created and destroyed in a given virtual environment and little ornothing may be known of any virtual machines in between the back-upwindows. In certain embodiments, logs of a hypervisor may indicate thecreation and deletion of a virtual machine, however there may be no wayto know the content of the virtual machine. In many embodiments, if amalicious persona has access to a hypervisor, that person may delete ortamper with the hypervisor logs hiding the fact that a virtual machineever existed.

Refer now to the example embodiment of FIG. 6, which illustrates asplitter integrated into a storage array at a given time. In FIG. 6,production site 600 has hypervisor 610. Hypervisor 610 has VM 631 and VM632. VM 631 sends IO 605 to VMDK 671, which is in VMFS 665, stored onvolume 660 on storage array 650. VM 632 sends IO 606 to VMDK 672, whichis in VMFS 665, stored on volume 660 on storage array 650. In thisembodiment, IOs 605 and 606 are intercepted by splitter 675 before theyare written to volume 660 respectively. In this embodiment, Hypervisor610 abstracts storage 650 and volume 660 from VMs 631 and 632 bypresenting each VM with an associated virtual machine disk. VMS 631 and632 have no knowledge of storage 650 splitter 675 or volume 660, ratherare aware of their respective VMDKs. In this embodiment hypervisor 610has no knowledge of splitter 675. In most embodiments, as a storagebased splitter may spit IOs at a storage level, a hypervisor may not beable to tamper with IOs in a storage array with the splitter. In almostall embodiments, a storage based splitter may not have knowledge ofvirtual machines in a hypervisor, even if the hypervisor is tamperedwith to try and hide activities of or existence of one or more virtualmachines.

Refer now as well to the example embodiments of FIGS. 7a and 7b .Splitter 675 also sends IO copy 609 to RPA 628. RPA 628 creates volume680 which is a copy of volume 660. Volume 680 contains a copy of VMFS665 as VMFS 665′. VMFS 665′ contains VMDK copies VMDK 671′ and VMDK672′. RPA 628 also has access to journal 660, which tracks the changesto the volume and allows any point in time access to volume 680. RPA 628receives IO copy 609 (step 700). RPA 628 replicates IO copy 609 (step710).

RPA 628 accesses a point in time using journal 660 and volume 680 (step750). RPA 628 mounts VMFS at the point in time (step 755). RPA 628parses VMFS (step 760). RPA 628 creates catalog or database 651 (step765). Database 651 contains information about virtual machines 631 and632.

In certain embodiments, database information about virtual machines mayinclude the number of virtual machines. In other embodiments, databaseinformation may include information about files stored on virtualmachines. In further embodiments, database information may includeinformation about what actions virtual machines are performing, forexample the IO activity of the VM as deduced from IO in the journal maybe stored in the database.

Refer now to the example embodiment of FIG. 8, which illustrates asplitter integrated into a storage array at a second given time. In FIG.8, production site 800 has hypervisor 810. Hypervisor 810 has VM 831, VM832, and VM 833. VM 831 sends IO 805 to VMDK 871, which is in VMFS 865,stored on volume 860 on storage array 650. VM 832 sends IO 806 to VMDK872, which is in VMFS 865, stored on volume 860 on storage array 850. VM833 sends IO 808 to VMDK 873, which is in VMFS 865, stored on volume 860on storage array 850. In this embodiment, IOs 805, 806 and 808 areintercepted by splitter 875 (as IOs to volume 860) before they arewritten to VMDKs 871,872, and 873 respectively. In this embodiment,Hypervisor 810 abstracts storage 850 and volume 860 from VMs 831, 832,and 833 by presenting each VM with an associated virtual machine disk.VMS 831, 832 and 833 have no knowledge of storage 850 splitter 875 orvolume 860, rather are aware of their respective VMDKs. In thisembodiment hypervisor 810 has no knowledge of splitter 875. In FIG. 8,as replication is performed at the volume level outside of thehypervisor, each virtual machine created in hypervisor 810 automaticallygets replicated.

Refer as well to the example embodiments of FIGS. 9a and 9b . RPA 828receives IO (step 900). RPA 828 replicates IO (step 910).

RPA 928 accesses a point in time (step 950). RPA 928 mounts VMFS 865′(step 955). RPA 928 parses VMFS 928′ (step 960). RPA 928 updatesdatabase 851 (step 965).

In certain embodiments, an RPA may periodically mount a point in time toupdate a database describing virtual machines in a hypervisor. In otherembodiments, an RPA may be set to mount a point in time in response toan event in a hypervisor. In further embodiments, an event that maycause a point in time to be mounted to update a database may be creationof a virtual machine. In most embodiments, a database may contain alisting of virtual machines and other information about the virtualmachines such as files accessed and processes started. In someembodiments, a database may contain a configuration of each virtualmachine. In certain embodiments, a database may contain changes tovirtual machine configurations. In some embodiments, a database maycontain the operating system of the virtual machine. In at least someembodiments, a database may contain an activity metric of the virtualmachines. In at least one embodiment, a database may contain IO memoryactivity.

Refer now to the example embodiment of FIG. 10, which illustrates asplitter integrated into a storage array at a given time. In FIG. 10,production site 1000 has hypervisor 1010. Hypervisor 1010 has VM 1031and VM 1032. VM 1031 sends IO 1005 to VMDK 1071, which is in VMFS 1065,stored on volume 1060 on storage array 650. VM 1032 sends IO 1006 toVMDK 1072, which is in VMFS 1065, stored on volume 1060 on storage array1050. In this embodiment, IOs 1005 and 1006 are intercepted by splitter1075 before they are written to VMDKs 1071 and 1072 respectively. Inthis embodiment, Hypervisor 1010 abstracts storage 1050 and volume 1060from VMs 1031 and 1032 by presenting each VM with an associated virtualmachine disk. VMS 1031 and 1032 have no knowledge of storage 1050splitter 1075 or volume 1060, rather are aware of their respectiveVMDKs. In this embodiment hypervisor 1010 has no knowledge of splitter1075.

Refer now to the example embodiment of FIG. 11, which illustrates recordof virtual machines over time. Volume 1180 has database 1150 whichrepresents point in time captures of the virtual machines of theembodiments of FIGS. 6, 8, and 10 over time. At time T1, hypervisor 1110had two virtual machines, VM 1131 and 1132. At time T2 hypervisor hadthree virtual machines, VM 1131, 1132, and 1133. At time T3, hypervisor1110 had virtual machines 1131 and 1132. Additionally, point in timeaccess 1155 and journal 1160 allow access to times T1, T2 and T3 whichenable a deleted machine, such as VM 1133 to be recreated although itmay have been deleted in the present time.

Refer as well to the example embodiment of FIG. 12. Database 1180 may beanalyzed (step 1200). Suspicious activity may be found (step 1210). Ifsuspicious activity is found, a virtual machine, such as virtual machine1133, may be restored using CIP access 1155 and journal 1160. Note, insome of the embodiments herein, for simplicity, time is referred to atT1, T2 and T3 but in most embodiments a storage base splitter may splitevery IO written by the hypervisor.

In many embodiments, a database recording virtual machine activity maybe regularly analyzed. In most embodiments, suspicious activity may befound by analyzing activity found in a virtual machine database. Incertain embodiments, where a database is updated each time a virtualmachine is created or deleted, the database may catalog each virtualmachine that existed in a hypervisor in a given period of time. Incertain embodiments, a database may capture suspicious activity of shortlived virtual machines.

In some embodiments, use of a high amount of storage may trigger one ormore entries in a database. In other embodiments, high use of networkresources may trigger one or more entries in a database. In otherembodiments, different events or actions may trigger one or more entriesin a database. In a particular embodiment, leak prevention software maytrigger one or more entries in a database. In most embodiments,suspicious activity may be found by analyzing a database.

In certain embodiments, once a virtual machine is suspected ofsuspicious activity, the virtual machine may be restored by returningthe replica volume to the timestamp when the virtual machine existed. Inmost embodiments, a restored virtual machine may be analyzed to see whatdata the virtual machine had and what actions it performed. In furtherembodiments, a suspicious time period may be identified and all virtualmachines within the suspicious time period may be restored an analyzed.In further embodiments, a suspicious time period may be identified by anexternal tool.

The methods and apparatus of this invention may take the form, at leastpartially, of program code (i.e., instructions) embodied in tangiblemedia, such as floppy diskettes, CD-ROMs, hard drives, random access orread only-memory, or any other machine-readable storage medium. When theprogram code is loaded into and executed by a machine, such as thecomputer of FIG. 13, the machine becomes an apparatus for practicing theinvention. When implemented on one or more general-purpose processors,the program code combines with such a processor 1303 to provide a uniqueapparatus that operates analogously to specific logic circuits. As sucha general purpose digital machine can be transformed into a specialpurpose digital machine. FIG. 14 shows Program Logic 1410 embodied on acomputer-readable medium 1420 as shown, and wherein the Logic is encodedin computer-executable code configured for carrying out the reservationservice process of this invention and thereby forming a Computer ProgramProduct 1400. The logic 1410 may be the same logic 1340 on memory 1304loaded on processor 1303. The program logic may also be embodied insoftware modules, as modules, or as hardware modules.

The logic for carrying out the method may be embodied as part of thesystem described below, which is useful for carrying out a methoddescribed with reference to embodiments shown in, for example, FIGS. 7,9, and 12. For purposes of illustrating the present invention, theinvention is described as embodied in a specific configuration and usingspecial logical arrangements, but one skilled in the art will appreciatethat the device is not limited to the specific configuration but ratheronly by the claims included with this specification. A processor may bea physical or virtual processor.

Although the foregoing invention has been described in some detail forpurposes of clarity of understanding, it will be apparent that certainchanges and modifications may be practiced within the scope of theappended claims. Accordingly, the present implementations are to beconsidered as illustrative and not restrictive, and the invention is notto be limited to the details given herein, but may be modified withinthe scope and equivalents of the appended claims.

What is claimed is:
 1. A system comprising: a hypervisor running one or more virtual machines; a storage based splitter, located on storage outside of the hypervisor; a replication appliance using the storage based splitter to replicate the one or more virtual machines, and computer-executable program logic operating in memory, wherein the computer-executable program logic is configured to enable execution across one or more processors of: intercepting, by the storage based splitter, IO to one or more virtual machine disks of the one or more virtual machines; wherein one or more virtual machine file systems are stored on the one or more virtual machine disks, wherein the one or more virtual machine disks are stored on the storage; wherein the intercepting the IO is not detectable by the one or more virtual machines, and wherein said storage based splitter is in communication with the hypervisor and a first volume; replicating, via the replication appliance (RPA) located remotely from said storage based splitter, the intercepted IO from the storage based splitter to replica images of the one or more virtual machine disks; the one or more replica images of the one or more virtual machine disks containing a replica of the virtual machine file system of the associated one or more virtual machines; wherein the replication is transparent to the one or more virtual machines and performed outside of the hypervisor, and wherein said RPA is in communication with said storage based splitter and a second volume; and periodically mounting one or more of the one or more replicas of the virtual machines to access the one or more virtual machine file systems to create entries, using the RPA, for a database tracking information about the one or more virtual machines running in the hypervisor.
 2. The system of claim 1 wherein the storage is a storage array and the computer-executable program logic further configured to enable execution across one or more processors of: analyzing the database to determine whether suspicious activity has occurred.
 3. The system of claim 2 wherein the entries of the database include the amount of network resources of each virtual machine of the hypervisor for each of one or more points in time.
 4. The system of claim 2 wherein the entries of the database include the amount of storage resources of each virtual machine of the hypervisor for each of one or more points in time.
 5. The system of claim 2 wherein a user may request recovery of a virtual machine in the database.
 6. The system of claim 2 the computer-executable program logic further configured to enable execution across one or more processors of: based on a positive description of suspicious activity, mounting a point in time replica image corresponding to a time of the point in time when the suspicious activity was identified; and examining one or more virtual machines at the mounted point in time for suspicious activity.
 7. A computer program product comprising: a non-transitory computer readable medium encoded with computer executable program code, wherein the code enables execution across one or more processors of: intercepting, by a storage based splitter, IO to one or more virtual machine disks sent from one or more virtual machines running in a hypervisor, wherein the storage based splitter is located on a storage outside of the hypervisor; wherein one or more virtual machine file systems are stored on the one or more virtual machine disks; wherein the one or more virtual machine disks are stored on the storage; wherein the intercepting the IO is not detectable by the one or more virtual machines, and wherein said storage based splitter is in communication with the hypervisor and a first volume; replicating, via a replication appliance (RPA) located remotely from said storage based splitter, the intercepted IO from the storage based splitter to replica images of the one or more virtual machine disks; the one or more replica images of the one or more virtual machine disks containing a replica of the one or more virtual machine file systems, and wherein said RPA is in communication with side storage based splitter and a second volume; and periodically mounting one or more of the one or more replica images of the virtual machine disks to access the one or more virtual machine file systems to create entries, using the RPA, for a database tracking information about one or more virtual machines running in the hypervisor.
 8. The program product of claim 7 wherein the storage is a storage array and wherein the code further enables analyzing the database to determine whether suspicious activity has occurred.
 9. The program product of claim 7 wherein the code further enables based on a positive description of suspicious activity, mounting a point in time corresponding to a time of the point in time when the suspicious activity was identified; and examining one or more virtual machines at the mounted point in time for suspicious activity.
 10. The program product of claim 7 wherein the entries of the database include the number of virtual machines in the hypervisor for each of one or more points in time.
 11. The program product of claim 7 wherein the entries of the database include the amount of network resources of each virtual machine of the hypervisor for each of one or more points in time.
 12. The program product of claim 7 wherein the entries of the database include the amount of storage resources of each virtual machine of the hypervisor for each of one or more points in time.
 13. A method comprising: intercepting, by a storage based splitter, IO to one or more virtual machine disks sent from one or more virtual machines running in a hypervisor, wherein the storage based splitter is located on a storage outside of the hypervisor; wherein one or more virtual machine file systems are stored on the one or more virtual machine disks; wherein the one or more virtual machine disks are stored on the storage; wherein the intercepting the IO is not detectable by the one or more virtual machines, and wherein said storage based splitter is in communication with the hypervisor and a first volume; replicating, via a replication appliance (RPA) located remotely from said storage based splitter, the intercepted IO from the storage based splitter to replica images of the one or more virtual machine disks; the one or more replica images of the one or more virtual machine disks containing a replica of the one or more virtual machine file systems, and wherein said RPA is in communication with said storage based splitter and a second volume; and periodically mounting one or more of the one or more replica images of the virtual machine disks to access the one or more virtual machine file systems to create entries, using the RPA, for a database tracking information about one or more virtual machines running in the hypervisor.
 14. The method of claim 13 wherein the storage is a storage array and the method further comprising analyzing the database to determine whether suspicious activity has occurred.
 15. The method of claim 13 comprising based on a positive description of suspicious activity, mounting a point in time replica image corresponding to the time when the suspicious activity was identified; and examining one or more virtual machines at the mounted point in time for suspicious activity.
 16. The method of claim 13 wherein the entries of the database include the number of virtual machines in the hypervisor at a point in time.
 17. The method of claim 13 wherein the entries of the database include the amount of network resources of each virtual machine of the hypervisor at a point in time.
 18. The method of claim 13 wherein the entries of the database include the amount of storage resources of each virtual machine of the hypervisor at a point in time.
 19. The method of claim 13 wherein a user may request recovery of a virtual machine in the database.
 20. The method of claim 13 comprising wherein an analysis tool may be used to determine malicious activity in the hypervisor and cause all virtual machines to be restored for the time period malicious activity was detected. 